Hydrostatic assemblies or transmissions typically include a hydraulic pump and a hydraulic motor that are coupled together so that fluid from the pump is used to power the motor. Although hydraulic devices, such as pumps and motors, have high power density, the amount of power output from a hydrostatic assembly is limited by the physical size of the hydraulic devices. When additional power is required for a particular application, hydraulic devices of a larger physical size are commonly required. In many vehicles utilizing hydrostatic assemblies, space is limited. As a result, increasing the physical size of the hydraulic devices may not be possible with such vehicles.
FIG. 1 schematically illustrates a known hydrostatic assembly 10. The hydrostatic assembly 10 includes a variable displacement pump 14 and variable displacement motor 12. The pump 14 and motor 12 are in fluid communication with one another through hydraulic conduits 15 and 16, one of which is under high pressure during operation and one of which is under a lower pressure during operation. Commonly, in addition to conduits 15 and 16, the hydrostatic assembly 10 also includes other hardware, such as manifolds and fittings, for fluidly connecting the pump 14 and motor 12. The hardware adds further size and weight to the hydrostatic assembly 10.
Another known hydrostatic assembly 20 is illustrated in FIG. 2. The hydrostatic assembly 20 includes a bent axis pump 25 and a bent axis motor 26. Fluid transfer between the pump 25 and motor 26 is through fluid conduits routed through fixed manifolds 27A and 27B attached to each porting cap and manifold 27C, which is interposed between the fixed manifolds 27A and 27B.
A need exists for increasing the power output of a hydrostatic assembly without significantly increasing the physical size of the hydrostatic assembly. If the size of the fluid connections between the pump and motor is reduced, the overall size of the hydrostatic assembly may be maintained even when the size of the hydraulic devices in increased.